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Why are pitot-static measurements preferred over other velocimetry techniques?
I believe hot wire anemometers (HWA, frequently used in wind tunnels to measure flow velocity) or other sensitive techniques could be used to determine the airspeed. Are there specific reasons for why the aircraft industry continues to use pitot-static instruments? Or is it just tradition?
A nice link on HWA's: The hot wire anemometer

My suspicion is that pitot tubes are extremely robust. By their nature, there's no air flowing through the tube and thus there's little risk of debris building up and blocking it. (Although I have had mudwasps build a nest in my pitot tube, which caused much hilarity when it clogged shut immediately after rotation.)

What would be the advantages of changing, and would those advantages outweigh the costs?  Remember the old adage: "If it ain't broke, don't fix it".

The pitot (more exactly: Prandtl) tube measures exactly the quantity which determines lift: Dynamic pressure. A hot wire or laser backscatter measurement has interpretation steps involved which the Prandtl tube doesn't need.

We have two closely related questions on this: here and here. Does one of them help?

@Pondlife They are similarly themed but I think the posted here is a lot more helpful. Thanks tho!

@KennSebesta Be careful with covering those! Wasps in the pitot tube have contributed to the crash of at least one plane.

@MichaelHampton 20 years in KY had taught me to put cowl plugs in for birds, but mudwasp nests in New England were new to me! I quickly learned the value of placing a yellow tennis ball on the pitot tube.

The linked article says that an HWA (hot-wire anenometer) is

fragile and requires complex equations to relate the sensed value to the fluid speed as well as correct for inherent, unavoidable nonlinearities as well as external factors such as fluid type, ambient temperature, humidity, and angle between the flow and the sensor.

Conditions in a wind tunnel or other lab equipment are far more predictable, and change much more slowly and much less, than those encountered during an outdoor flight through variable weather.
Although industrial variants of the HWA don't expose the fragile sensing wire to damage or dirt accumulation (the dirt as thermal insulation causes the sensor to report incorrectly; rain or ice would still affect an aircraft-mounted one), they still need to correct for density, humidity, temperature, and flow angle.  A four-dimensional lookup table takes a lot of work to create and store.  Outside the lab the pitot tube is more reliable, even if it is more "primitive."
HWAs have been flown, but only as test equipment, not as sensors for primary flight instruments.  For example, this set of HWAs flew on an F-15B to characterize flows in the boundary layer, sampled many thousands of times per second, far more sensitive than a pitot tube.  But between each 30-second measurement interval, the HWAs were retracted inside the airplane for protection.

Thanks for the answer. A very interesting point on them being used on the F-15!

Hot wire anemometers are great for measuring turbulent fluctuations on a very fine timescale (say kHz). This is really not needed for aircraft speed. The very same wind tunnels that use HWA or LDA (laser Doppler anemometry) or PIV (particle image velocimetry) for detailed measurements themselves usually use Pitot tubes to measure the reference windspeed in the tunnel. It is robust, remains calibrated and will smooth out the fine turbulent fluctuations, which is actually a good thing if you are interested in the speed only.

There are quite a few reasons. First off, as everyone has already mentioned, HWAs are quite fragile and somewhat more complicated to decode (though the latter is a non-issue with modern electronics). More importantly though, a pitot-static measurement offers some distinct advantages specifically as far as aviation is concerned.
On the face of it, a pitot-static system is very simple, both in concept and implementation. A typical integrated pitot-static tube measures total pressure at the pitot port and has a series of equally spaced holes around its circumference (in the cylindrical portion) to measure static pressure. In common use are also pure pitot tubes, wherein a static reference comes from the static port altimeters are connected to.
It is important to note that the tube itself does no measurement. Merely, it provides a reference location for a sensing element to be connected via pipework of some type (usually a mixture of rigid and flexible hose, depending on the application). It is at the sensing element where the magic happens.
When a differential manometer is connected across the total and static references, it is able to directly measure dynamic pressure in that location. This follows from incompressible flow and the Bernoulli equation, namely $P = p + q$, where $P$ is total pressure, $p$ is static pressure and $q$ is dynamic pressure. Upon expansion, $q = 1/2 \rho U_{\mathrm{inf}}^{2}$ where $U_\mathrm{inf}$ is the free stream velocity of the airflow giving rise to $q$, and rho ($\rho$) is the free stream air density.
When we assert a constant rho of 1.225 $kg/m^3$, we can rearrange for free stream velocity: $U_\mathrm{inf} = \sqrt{2 q / \rho}$, or if we factor out $k = \sqrt{2 / \rho}$,  $U_\mathrm{inf} = k \sqrt{q}$ - a simple square root relationship which can be implemented mechanically or in software quite easily.
Where this is particularly useful is in aerodynamic calculations during flight. As every important flight parameter (lift, drag, control input, etc.) is directly correlated to $q$, having an indicated airspeed (IAS) also directly correlated to q simplifies a pilot's job drastically. There is now ONE stall speed for each configuration. The feel of the aircraft is exactly the same, no matter the air temperature, the list goes on. The value of this simplification in reducing pilot workload cannot be overstated.
This is why, for any normal flight operations outside navigation, indicated airspeed derived from directly measured dynamic pressure is by far the most useful speed measurement to have. Navigation is secondary and for that there are conversion tables, DME and GPS.
It should be noted, that the raw $q$ measurement from the pitot-static system is almost never left unadjusted for commercial and military applications. Anything from the pitot port's position to compressibility effects must be adjusted for in order to preserve the IAS relationship a pilot expects, which is why modern commercial and military aircraft first convert IAS to calibrated airspeed (CAS), which accounts for the pitot-static system's position error and then into equivalent airspeed (EAS), which further accounts for compressibility as soon as the incompressible flow assumption breaks down (usually at any Mach number above 0.3).
It should further be noted that both Reynolds number (related to true airspeed or TAS) and Mach number will have an effect on aerodynamic forces, but those effects are usually small (during subsonic and low transonic flight) compared to the effect of dynamic pressure and may or may not be accounted for in other ways (i.e. adjustments to the fly by wire system, if present).

Welcome to Aviation SE!  I admire your technical-but-readable writing style.

Thanks, happy to help!

Most modern car engines have a computer to balance fuel-air mixture, ignition timing and other factors to give best performance or fuel economy. A hot-wire Mass Air Flow (MAF) sensor is a very common way to supply air flow data, there are also cold-wire versions. Although they are very reliable for that application there are a few issues which would make them less than ideal for aviation:

They are relatively fragile, fine for automotive air flows but they wouldn't stand up to higher air flows
They are sensitive to oil, aerosols and other airborne contaminants which would effect their accuracy. These accuracy issues can be hard to detect as they aren't outright failures. In a car an inaccurate air flow sensor leads to inefficient combustion which limits power and efficiency, in flight inaccuracy would be a major safety issue
Cold wire systems are slower to respond to airspeed changes

The electrical airspeed sensors I know of are all pressure transducers, which are accurate and don't have the flaws I listed above.
The thing you also have to be aware of is that hot or cold wire systems need a laminar flow of air to be accurate, you'd still need a pitot system or something similar to direct the flow of air over the sensor for it to give the correct reading.
Of course, the biggest drawback to any computerized sensor system is that they are reliant on electrical power.

HWA sensor in cars benefits from at least 3 additional advantages: An air filter to limit the dust in the airflow, no need for an absolute (long-term) stability and frequent shutdowns of the engine when a maintenance (by self-heating) can be performed. It is also clearly not that much important - the engine can be acceptably controlled by the MAP (pressure sensor) alone. Not to say that the car is inherently safe even with completely failed engine.

Not disagreeing with you @fraxinus, I would say that many non turbo cars don't have a MAP, if the MAF fails the ECU falls back to static maps. The engine will still work with reduced power and/or efficiency.

Also, there would seem to be a considerable amount of redundancy in the automotive case.  The air flow sensor isn't the only sensor in the system.  If it reads too low, the exhaust sensors will detect a too rich mixture, and the ECU could be programmed to correct for it.  Using it as the direct source of air speed means there is no redundancy.  (Other than "seat of pants" flying, of course.)

Not really @jamesqf, the computer may know something is wrong but often times you'll have to some detective work to trace what's going on. But, it isn't critical. With an aviation application you'd have at least 2 of everything important anyway, but as we've seen that doesn't always solve the problem

"The thing you also have to be aware of is that hot or cold wire systems need a laminar flow of air to be accurate" This is nonsense or some serious misunderstanding. Hot wire systems are the best instruments to measure turbulence on very fine time scales. They are the most important type of instruments that were used to study the fundamentals of turbulence for decades.

authors: Vladimir F Героям слава


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Conflicting A320 Climb Profiles
In the Airbus brochure (more like a book) Getting to Grips with Aircraft Performance, the standard climb profile for the A320 family is mentioned as

250 kt / 300 kt / M0.78

With this accompanying chart:

(image taken from Getting to Grips with Aircraft Performance by Airbus)
So these speeds (the first two phases) are certainly IAS.
The book mentions the reason for the initial 250 kt to be due to ATC restrictions <10k ft. I ran a search and found this to be true.
However, very ironically, this website (eurocontrol.int), gives the following figures:

290 kt / 290 kt / M0.79

(image taken from eurocontrol.int)
As visible from the chart, even this source clearly states that the speeds are in IAS.
TL;DR
Can someone reconcile this conflict: How can eurocontrol.int claim that the A320 flies at 290 kt under 10k ft, with Airbus's own book claiming otherwise, and why do these sources differ (250/300/0.78 vs 290/290/0.79) ? Which profile is more accurate to what real pilots fly?

The first profile you show is a typical climb profile for the A320. You have the usual 250 KIAS constraint below 10,000 ft and then climb at 300 KIAS until reaching the climb Mach of 0.78. The exact values of 300 and 0.78 will however differ for every flight. These are just typical values.
The optimal climb speed and mach number is determined by the FMGC (Flight Management and Guidance Computer) on the A320:

The FMGC computes optimum speeds, based on:

Gross weight (GW)
Cost index (CI)
Cruise flight level (CRZ FL)
Wind and temperature models
Performance factor

When there is no time or speed constraint/limit, ECON SPEED is the optimum speed for the selected cost index. It refers to fuel and time cost, and not directly to fuel saving. The FM calculates ECON CLB, ECON DES and the associated top of climb and top of descent as a function of cost index, cruise FL, and meteo data.

(Airbus A320 FCOM - Autoflight - Flight Management)
The primary way to influence these speeds is by selecting a different cost index. The cost index to choose is usually selected by the airline. A lower cost index results in less fuel burn, but longer flight time, and vice versa.
The second profile you show is from the Eurocontrol performance database. This is information for air traffic control and planning purposes that shows the aircraft's capabilities at typical weights. This just means the A320 is capable at climbing at 290 KIAS (even below 10,000 ft) until reaching Mach 0.79. Note that the page then also shows the climb rate that can be achieved at these speeds, which is helpful for anticipating possible future conflicts with other aircraft. The actual profile flown can however differ from this one. Climbing at lower speeds would then result in higher climb rates and vice versa.

The 250kt speed limit below 10'000 is not universal. It depends on the airspace class and country-specific rules what the exact limits are.
The Airbus manual has provided a climb profile for the lowest common denominator, which is climb with the speed limit imposed. In theory one could execute that climb profile in any jurisdiction.
The Eurocontrol manual is specific to the situation in most EASA countries, where speed limits are different. For example, while in the US class A airspace is never below 18'000, around Amsterdam Schiphol airport the class A starts at 1'500, and a high speed climb is preferred. See What is the speed limit in European airspace? for more information about speed limits in EASA-land.

"a high speed climb is preferred" -> are you sure? Even if it is in class A airspace, every SID chart of Amsterdam contains this speed constraint: "SPEED: MAX 250 KT BELOW FL100 UNLESS OTHERWISE INSTRUCTED".

@Bianfable The "otherwise instructed" is pretty much the norm. Departure typically approves high speed climb on initial contact.

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What exactly happened in this bird strike incident?
This Boeing 737 was hit by a bird and continued all the way to its final destination, from Prague to Las Palmas.
What actually happened here? Was the incident considered a bird strike or an engine stall? Can an aircraft continue to its final destination after a bird strike?

Do you have any reference other than the link in the question? Questions should be self-contained.

The video is now private. :(

I can't view the video, it is private now. Can you please add a text description of what happened and a few references to some official source or at least well-known news/media sources?

Since it hit a bird, it was a bird strike. Nothing else matters for that classification.
The puff of flame suggests there probably was a momentary compressor stall. That is the compressor was unable to maintain the pressure as the flow was disrupted by the bird, the flow through the engine slowed down for short while, some extra fuel accumulated in the engine and as the flow restored, the extra fuel burned past the jet, creating that puff of flame.
The engine did not flame out, that is, it continued to run. Older engines tended to get into a repeated cycle of stalls once they stalled as the accumulated fuel from one stall would cause the pressure to increase beyond capability of the compressor and cause another stall, but modern engine computers will automatically restrict the fuel flow to prevent that.
The aircraft continued, because the engine was running and all parameters (RPM, temperature, vibrations, pressure ratio, oil pressure) were indicating normal values.
If the engine stopped, or if some indications were out of tolerance, they would have to return, since two-engined aircraft are required to land as soon as possible when one engine fails. But it clearly did not and they continued (and may not have been aware of the bird strike at all until inspection after landing, because the stall handling is automatic and if no values were out of tolerance, they would not get any warnings).
The engines are designed and tested to continue running after ingesting  a small bird [1], so this was actually the expected outcome. The test usually involves launching dead chicken into the running engine (on the static test bench) from a chicken gun [2]. Said gun is also used for testing canopies and windscreens. Frozen chicken are occasionally used too; contrary to the urban legend not due to stupidity, but intentionally as tougher version of the test [3].

Comments are not for extended discussion; this conversation has been moved to chat.

That test is also very effective at ensuring not only that the engine continues to run, but that the chicken is thoroughly dead.  There is not a single documented case of a live chicken sneaking through quality control and walking away from the encounter.

I find it somewhat hard to believe that the pilots could be unaware "of the bird strike at all until inspection after landing"; unless flames shooting out of a jet engine is a normal occurrence in air travel, wouldn't at least some of the passengers have noticed, been very concerned, and notified the cabin crew, who then would (presumably) have let the pilots know at some point that "hey, just so you know, the number one engine was spewing flames just after we took off"?

@Sean - A puff of flame (lasting approximately 1/5th of a second) is hardly "spewing". Probably they just blinked and missed it

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Are these two aircraft too close to each other?
One aircraft is taking off and another is quick to land after it. Are they within safe limits?

It's not a duplicate, unless the other question asks about this pair of airliners...

@DanieleProcida: Not a duplicate, correct, but opinion-based unless we do a clever calculation based on the optical characteristics of the lens.

@mins Clearly not opinion-based. My answer below is based on facts about how ATC and airports work, and requires no clever calculations.

This is the Birmingham Airport England . Runway length 3,052 meters. On the video you can see that between takeoff on landing only 31 seconds gap

What is the problem you see? Until the runway is empty, the approaching aircraft is only allowed to continue the approach, but not cleared to land. So the crew is ready to abort the landing if the decision height is reached before the clearance is provided by the tower. The decision height (or MAPt) can be very low and is likely closer to the threshold than the 31 seconds you measured.

They're not too close
They (almost certainly) are not closer to each other than is allowed.
It would be quite extraordinary if a pair of airliners at an airport were allowed by air-traffic control to approach each other in violation of limits, which not only include the distances of time and space demanded by safety, by additional margins as well.
If there had been a violation of those limits, it would have recorded as a matter of course and investigated.
On that basis I think it's safe to say that it's extremely unlikely that approach limits were violated.
The camera doesn't lie, but YouTube doesn't tell the truth either
A second point is that it is extremely hard for human beings to judge distances, positions and speed in three-dimensional space.
Frankly, it's a wonder that we're ever able to play table-tennis, but the fact is that when you're looking at a pair of aircraft you have little chance of accurately judging what they are doing in relation to each other.
That's especially so when the aircraft are on YouTube. I bet even a champion wouldn't be able to play table-tennis on YouTube...

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What are the disadvantages of using just rudder to roll an airplane?
Ultralights with slight dihedral will roll and yaw on rudder input (e.g the Bloop 3, Maxair Hummer) so some don't have ailerons for the sake of simplicity. Is this kind of control input advisable, or are there disadvantages?

Related

differential elevator is much better choice if you design the airplane with simplicity in mind from scratch.

Not sure I'd say it's a "better" choice, but it's at least as valid, and the mechanical mixer required is pretty simple to build.  The roll authority is pretty small, but as an adjunct to rudder/dihedral, it should improve the coordination of turns.

It works in a half-assed way but the key word is half-assed. You'll always be skidding around the sky since sideslip is required to obtain and maintain any rolling moment.  Control response can be somewhat laggy, since you have to induce a skid and wait for the roll, depending on how much dihedral you have.  So to have something approaching snappy control response, you need way more dihedral than is necessary for normal lateral stability.  The inability to cross control limits the ability to handle crosswinds and prevents you from using sideslip to increase descent rate.
So it works after a fashion, but will never be as good as full 3 axis.  The thing with ultralights is that because of the really low mass/large surface area, they are really strongly affected by turbulence, and when close to the ground, half-assed control authority is the LAST thing you want.
Control authority is not a place I would cut corners in the interest of simplicity.  I think that the attraction of 2 axis control for ultralight designers was in the idea that non-pilots getting into ULs would think "Hey that must be only 2/3rds as difficult to learn as 3 axis.  Must be better."

Yes that is one of the benefits of the inverted V tail (Molt Taylor, inventor of the an FAA certificated flying car in the early 50s, was a big advocate).  But the rolling moment you get from an inverted V tail is pretty mild unless you make it really big and then you are building way to much tail volume (area x arm), so you are still dependent on dihedral.  Plus the other negative from V tails, a tendency to yawing moments in gusts (tail wagging in bumpy air) you have to live with.

Rudder only limits banking as described very well by John K, and might be a distorted view of increased safety by helping the pilot to not become disorientated.  It may also be an attempt to not over stress the structure or prevent a stall in a high G turn.
After considering John K's comment it appears to me this is more a marketing or cost savings stunt, then a safety consideration.
A stall in a skid or slip is all that is necessary to enter a spin! So, essentially you are trading a less hazardous situation (disorientation) for the biggest pilot killer on the planet! (spin)

source

I have some tens of hours flight experience with radio control aircraft that fly this way -- throttle, elevator, and rudder.  How well it works depends very much on how much rudder authority you have, and how much dihedral.
I have seen and flown aerobatics with these no-aileron aircraft, including prolonged, controlled inverted flight (tricky, because yaw-roll coupling reverses when inverted), outside snap rolls (again, roll is reversed relative to rudder and the aircraft may tumble if the wing unstalls before rudder is neutralized), as well as more conventional slow rolls, chandelles, Immelman turns, etc.
I wouldn't expect an ultralight to be flown through any of these maneuvers (at the least, you'd need full aerobatic stress limits), but I would expect one to fly well in normal operation if the rudder authority and dihedral are correctly balanced.  If you're interested in building one and don't want to follow an existing design, I'd very strongly recommend building a radio control test model to verify the setup (tail moment, surface deflection, CG position, thrust axis, etc.) before cutting any tubing or fabric.

The configuration works perfectly fine within its limitations, just as hang gliders work fine within their limitations.  The issue is what is optimal on a machine with wings and tail and control surfaces, and the acceptance of the limitations of skid-turning for the sake of some simplicity gained by leaving out the ailerons will be considered a poor choice by pilots experienced on normal aircraft.  I mean, there's a reason in the end as to why almost nobody does it.

It need not look and feel any different to the pilot from an original no-pedals Ercoupe (ailerons and coupled rudder) -- in my experience (with R/C) the "skidding turn" isn't noticeable (it might be more so from the pilot's seat, of course).  There have been other factory-built GA aircraft that flew with rudder and no ailerons, mostly before WWII, as well as the whole Pou de Ciel family (of which only one model is known as a pilot killer).

Yeah and they pretty much all suck.   The Ercoupe was an interesting one.  To land it in crosswinds they designed a crab tolerant gear because that's how you had to land it.  I would say most Ercoupes today have had separate rudder controls added by STC because most pilots hate not being able to cross control the airplane.

At the time the Ercoupe and Pou de Ciel designs appeared, crossed controls were considered as much a pilot killer as they were necessary (most aircraft also lacked flaps at that time).  Cross up between a slip and a skid at low altitude, you can wind up in a splintered, burning wreck instead of shortening your approach.  These aircraft were attempts to prevent this, and some were "spin proof" as well.  They may not fly the way you're used to after learning three-axis control, but they fly and some fly very well.

The feature that made the Ercoupe spin proof was a limited elevator range that prevented stalling deeply enough to enter a spin, not so much the interconnect (modern airplanes barely need any rudder to coordinate turns anyway).  That also limits things you can do however, like have flaps.  And its accident record is, surprisingly, no better than its contemporaries.  In any case, forget about RC... believe me if you fly full size aircraft and are presented with a 2 axis airplane you will not like it once you experience its limitations.

Probably the Pou de Ciel family is a better example for discussion; despite being homebuilt and underpowered, the only one with a really poor safety record is the one that's effectively a plagiarized knock-off (Model 6?) by a designer other than Mignet.  Rudder and elevator (by pivoting the forward wing), and after the design mod to eliminate the tuck-under, many hundreds flying and a safety record no worse than other homebuilts.  Almost possible top build one as a USA legal ultralight, too -- probably possible, with modern materials.


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How is the due date for landing gear replacement determined?
I want to know how calculate the due date of Boeing MD-83 Landing gear replacement (it is every 10 year or 20000 FC).
Is it calculated from the installed date or shop visit date?

Welcome to Aviation.SE. This sounds like a question that should be answered by the OEM or qualified mechanic.

@Notts90 That would indeed be a good way to get an answer, but it still seems to me that the question could be answered by someone here. It's specific and factual, so why not?

@Pondlife It could but I doubt such information is readily available on the internet to provide a credible reference (happy to be proven wrong). Hence the best place to get an official answer would be the OEM.

@Notts90 Information not readily available through Google is exactly one of the reasons why this site exists, to answer difficult questions like this. Some of us have OEM books or knowledge.

@JonathanWalters Yes but for a safety aspect I think that isn't a good enough source. I think you should only take that information from an OEM source (in person, book or website). I'm not saying we can't answer it here, just the best answer would be via OEM in this case.

@Notts90 True, if such questions are coming from professionals, or the "qualified mechanic" as you say, this may not be the best forum. However, there is a place for such questions even if asked by professionals, but especially if asked by the curious non-professional.

To my knowledge, all lifed components are tracked from installed date. That is from personal experience, but I can certainly have a look through the regs to find an official source, if you require.

Aren't some components checked or repaired after a given number of cycles rather than after a number of days?

Oh, absolutely. That is actually what FC refers to (flight cycles) vs FH (flight hours). Really depends on the component. Obviously it wouldn't make much sense to limit landing gear based on hours flown, but rather on flight cycles. That having been said, components are often limited in both time and usage. Something along the lines of overhaul at x months or y flight cycles/hours, and using whichever is more limiting, is pretty common. The question is simply asking for when the cycles/hours or days are tracked from though. That would be install date

Ah I understand now, I missed the meaning of the question, as you may have guessed already.


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Can the Mexican presidential aircraft be sold?
I have read that the next Mexican president is trying to sell the B787 that serves as presidential transport, and that it was already made an offering to Boeing for it.
As far as I know, the VIP/presidential aircraft are more or less custom made, so it's hard to imagine that anyone would buy it (I'm guessing an airline would retrofit the plane for his own configuration and that would be more expensive than buying a new plane).
But perhaps the manufacturer would use it for leasing purposes.
Then, it is viable to sell this presidential aircraft (or any other)? How much can be paid for it (compared to the initial value)?
Reg: XC-MEX

Not sure about that specific aircraft, but the Dutch government recently sold its transport (a Fokker 70) for the royal family in anticipation of the arrival of its more capable replacement.
I've seen the aircraft many times before it was sold.
I've also seen President's Eisenhower's personal Beechcraft Twin Bonanza, which has been called the very first dedicated Air Force One, which is currently in a private collection in Canada. Not sure when it last flew, but the owner tries to keep his entire collection airworthy and once in a while takes one of them out.

The type of presidential transport matters. Most governments use regular business jets that can easily be sold off on the commercial market, just as the Mexican president is now planning to do. But Air Force One for example is heavily modified and is actually classified as a military plane. Therefore it cannot be sold just like that. If it was decommissioned it would probably either be scrapped, or at the very least completely stripped of all special/secret government technology.


text:
Where can I find official information about a recent crash in Mexico?
I have heard about a helicopter crash involving an Agusta A 109 in Mexico, that seems to be causing some turmoil due to the deaths of a newly-elected governor and her husband. Is there any info about what happened, metars, logs or something?
Aviation herald does not have any info about it.

This happened less than 24 hours ago, you may be able to look up Metars for the area (if there is a historical weather service for the area), but they won't be releasing any kind of report, logs, pilot history, etc, for quite some time.

Suggest you check here in the next few days.  The ICAO Annex 13 investigating country is Mexico, who are not quite as eager to please public curiosity as some other reporting states ...

Current investigation status. Update, search for "XA-BON" here.

@mins, when You just post the link I give a fast view and few time later was deleted,  It seems to the info was reserved by the Transport Ministry, so it looks something suspicious.

"You just post the link I give a fast view and few time later was deleted". The two links above still work and the domain gob.mx is the portal of the Mexican administration.

@mins, I didnt mean as a complain, Indeed there are certain articles, but there were one that started to read but later there werent anymore.

and as far as I can read Spanish (not much), the info was reserved as matter of national security, and there were politicians arguing this was not an accident, and the aviation herald didnt show any info in the date nor later.


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Why would an ILS have a glide path angle less than the preferred 3°?
According to EASA the preferred Glide Path Angle is 3°:
EASA Easy Access Rules - Page 22 - 4.1.2.1.
There are some airports (e.g. Larnaca 2.75°) which are using a lower Glide Path Angle than 3°. Using a steeper angle (e.g. London City 5.5°) makes sense due to obstacle clearance. But what's the reason for using a flatter angle than recommended?

I thought it may be to deconflict the approach with another, but there are no other airports around Larnaca, so at least in that case it won't be the reason.

Shallow glideslopes were usually to accommodate military aircraft that needed to have higher thrust settings on approach and so benefit from the shallower path.  Does Larnaca see significant military traffic?

@JohnK Bingo. Would you care to add that as an actual answer?

Larnaca has never had much military traffic. It was used by the British as an airbase but long before it became an international airport (and I suspect long before "high thrust" aircraft). Unless John's theoretical answer can be corroborated, I don't think it makes a very good one.

@JohnK That line of reasoning breaks down at KTUL, which has a 2.75 degree GS angle landing south, but a standard 3.0 degree GS landing north. Neither is a recent change, as far as I can remember. Most military bases have standard 3-degree ILS approaches; shouldn't we expect to see a number of hold-over shallower approaches at those, if that's who originally needed them?

@expeditedescent I don't have any source info; it's only a dim recollection from the past.  I found some commentary on PPrune that supports it, but not sufficient for an answer.

@Jamiec The bit about military using shallow slopes was an artifact of earlier slow-to-spool engines that could be a problem if the glide path requires you to approach closer to idle.

@JanHudec Akrotiri just along the coast to the west with conflicting runways

@Arkhem. Akrotiri isn't ‘just’ along the coast, it is over 30 nautical miles, and at the point the extended centrelines cross, Akrotiri is much closer, so the approaches would be at different height there if the point wasn't moot because glideslope does not extend over 10 miles anyway.

@Arkhem, before I wrote the first comment, I did pull out skyvector and did check the distances (the parallels are drawn 30' apart, so they are 30 nm apart—that's how you get scale on maps that don't preserve scale globally, as navigation maps often don't, and the reason why nautical miles are used).

@JanHudec I hadn’t checked the actual distance. However I often fly into Akrotiri and when the winds are light or N/S ATC has to deconflict the traffic and I believe the holds etc are non-standard.

@Arkhem, do they deconflict it on final though? The complete arrival procedures are much longer than 30 nm and surely some combinations of them conflict, but it shouldn't be on final where the glideslope angle matters.

I won't pretend that I understand the physics of this, but one possible explanation is in FAA Order 6750.16E - Siting Criteria for Instrument Landing Systems. Section 3 discusses terrain effects on the ILS signal, and it notes that approaches that are partially over water may have signal quality issues. One way to address that is using a lower glide angle, per this section on page 3-4 (emphasis mine):

Where the Fresnel zone is smooth but not consistent, as where the
approach path is partially over water, a change may be encountered in
the received signal as the coefficient of reflection changes abruptly.
This effect is unavoidable; however, it can be minimized by
establishing the lowest possible glide angle (and, therefore, the
lowest possible grazing angle) and/or locating the glide slope
antennas within the specified criteria, so that the change in the
received signal does not occur within a critical part of the approach.

I don't know exactly which procedure you're looking at, but Larnaca is a coastal airport and it looks like approaches to 04/22 are at least partially over water.
I have no idea if the same issue occurs with other types of terrain. Someone mentioned in comments that the ILS at KTUL (Tulsa, Oklahoma) has a 2.75° glideslope landing south, but 3° landing north. KTUL isn't on the coast and there are no large bodies of water directly north of it. Maybe the same signal issue occurs there for different reasons, or maybe there's a completely different reason.


text:
What does gravity compensation do in flight control?
In flight control designs for lateral directional movement, there is a block named "gravity compensation". This block changes yaw rate measurement from "$r$" to "$r-g/Vcos(\theta)sin(\phi)$" before it is sent to the controller. How does this block change the equation of motion?

can you provide an image example? have you studied the equation of motion?

I provided an image example

That term is a feedforward.
It simply makes sure that during a turn the rudder will anticipate the need for that $r$ component and thus helps making the turn coordinated.
Since the term is complete (i.e. there is also the $\theta$ component) this will work also for climbing/descending turns.

It looks like a feedforward. But note that it is fed to the feedback controller. If it was feedforward, it should be added to the output of the feedback. Can you provide a reference?

@shooshool no, it is a feedforward. the fact that is added to $r$ instead of the rudder command does not change its nature. source: I've implemented it several times on our research aircraft.

Should this feedforward be considered when the controller block is being designed? Or the controller is designed without considering the effect of feedforward and then the feedforward is added?

@shooshool if it is there, usually the controller is designed assuming that the feedforward is working as intended, i.e. lowering the load on the controller, but that's a different matter not for this stack


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How do I fly direct to the VOR on a VOR missed approach?
Below is the Truth or Consequences VOR-A Approach in New Mexico, USA.

The Missed Approach procedure for this approach requires that you do a left climbing turn to 8300 feet direct to the VOR.  My question is what radial should I dial-in to go direct to the VOR?  Should I fly the reciprocal radial of the final approach course (342 degrees) or should I turn to a reciprocal heading (342 degrees) and then center the needle to find the radial I should fly direct to VOR?
Note:  There is only 2.4 nautical miles between the VOR and Missed Approach Point so trying to intercept the reverse radial in 2.4 nautical miles is a little tricky here especially with the CDI being so sensitive that close to the VOR.

If I were to fly it, I would start a climbing left turn (according to the MAP described on the chart) and simultaneously start turning the OBS to keep the needle centred until I am after a +/-210 degrees turn and then centre the needle with a TO flag on the HSI/CDI and fly direct to the station on a present radial.


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What should the Attitude Indicator be reading when in straight and level flight?
I recently replaced the vacuum instruments in my plane, a Piper PA-28-180, to a GI-275 Primary Flight Display (PFD).  This plane is being used for training at my local flight club.
Since the new system has been installed the lead flight instructor has complained that the attitude indicator is reading 5 degrees too high.  When in straight and level flight at a density altitude of around 10,000 feet, the attitude indicator is reading an attitude of 5 degree nose up.
It is my understanding that most airplanes require a positive angle of attack to generate lift.  It seems to me that 5 degrees nose up would be about right for a 180 horsepower airplane with 2 people cruising at a density altitude of 10,000 feet.
I am told that with the old vacuum systems that pilots are instructed to move the position of the miniature airplane on the attitude indicator to be level with the horizon in level flight and that this is actually a fudge factor and not a true representation of attitude.  With the PFD displays the FAA does not allow the pilot to move the position of the miniature airplane because they want the attitude indicator to read the correct attitude.
Is my lead flight instructor correct that the attitude indicator should read level with the horizon in level flight?

Closely related

Ask your instructor to do slow flight (nose high but level flight) and explain why the attitude indicator points up if the aircraft is not climbing.

An attitude indicator could show anything at straight and level flight, even upside down or 90 degrees sideways. You might want to consider finding another flight club where you can rent your airplane for training.

Simply put: straight and level flight does not always mean you’ll have 0 pitch. If the C.G. is more forward, you’ll have to “pull up” the additional force (WEIGHT) from the nose to have VS = 0 FPM, i.e., pitch > 0.

Do you have the option of displaying the FPV (Flight Path Vector)?

@skipper44 You can only get the FPV if Synthetic Vision is enabled which costs an additional $1000 which I didn't find worth the additional cost.

It's just that the FPV is a facility that can put to rest all unresolved doubts/comments/questions on the subject of this page provided it is taught and understood properly. You could task your CFI to develop a practical lesson plan.

Essentially this question boils down to, what is the definition & reference for "0" pitch?
"Level flight" would be a problematic answer, because as Ron Beyer notes, your deck angle for level flight varies with airspeed (among other things).
With the old attitude indicators, one could set the airplane symbol to whatever you wanted, so setting it so that at "these" conditions "today", level flight matches up with 0 pitch displayed is viable.  Maybe not wise, but that's its own discussion.  (For instance, if you lose your airspeed indicator & have to use known pitch & power settings, you've just introduced a delta to every pitch setting that's published, by tweaking the attitude indicator like that.)
With modern AHRS and INS/IRS/INU's, the answer to the question becomes simple... 0 pitch is whatever the airplane/software manufactures say it is, and that's that... no adjustments available.  That zero reference typically corresponds to a 0 AOA in level flight or level attitude on the ground or something like that.  Thus, "level flight" generally corresponds to some amount of nose-up attitude.  The 737 is about 3-4 degrees nose up, although the difference between clean & 200 knots vs clean & 320 knots is significant; then you start adding flaps or changing the gross weight & everything changes some more.
I don't know if 5 degrees is right or not -- it certainly seems in the ballpark.  The lead CFI may be right that it's off, but if he's claiming that it's off by the full 5 degrees I'd be doubtful.  If the pitch shows zero when taxiing on a level surface, I'd tend to think that the system is okay.  If it's showing +2 or +3 degrees at that point, it might be worth consulting whoever installed the new system & asking if that's right or if a sensor needs some adjustment.

Simply make sure you are on a level surface and see what t5he pitch attitude is.  It should be zero as Ralph J indicates.  In the jets I fly, level flight is 3 degrees nose high.    In a smaller airplane close to its surface ceiling and max weights, 5 degrees nose up seems quite reasonable.

+1... The only objection I take is "That zero reference typically corresponds to a 0 AOA", 0 AoA doesn't mean level flight either, you can point straight up/down and have 0 AoA. Did you mean "0 AoA on the ground"? It really is just "aircraft attitude relative to horizon".

The “zero reference typically corresponds to a 0 AOA” is a circular definition, because the reference angle for AoA is just as arbitrary, so it just says AoA and AI are referenced to the same plane (which is usually the case if AoA is referenced to the fuselage and not the wing chord line).

Now what's missing is finding what is the reference plane for a PA-28. In airliners the cabin floor usually is, and is usually level on the ground. But that might not be the case for small piston singles like, which often sit rather nose-high on the ground for propeller clearance.

The avionics shop told me that the calibrated the GI-275 by leveling the plane according to the manufacturers recommendation and calibrating that for 0 pitch.

The direction your thoughts have taken is absolutely correct. While we can all understand the simple expedient of aligning the airplane symbol with the horizon, the practice is incorrect when referring to actual pitch attitude.
It's possible, but unlikely that an uncomplicated design like a PA-28 have a 0 deg pitch attitude in 'normal' straight and level flight at normal cruising speeds. 5 deg seems to be more likely correct, though it seems also too suggest a slower speed. Maybe the CFI is referring to the worst case to emphasize his objection.
I remember transitioning from a 2 seat trainer to a high performance 19 seat turboprop and being embarrassed because I would dutifully put the nose of the airplane on the horizon of the ADI to level off and almost instantly develop a 2500fpm descent as a precursor to the ensuing camel ride. The Instructor, had superannuated not a month earlier from flying the wide body Airbus 300 and hadn't dealt with 250 hour trainee pilots before. Ironically, the A300 can be flown beautifully using simple pitch and thrust values.
The only saving grace for me was that the series of trainees that followed were a shade worse if anything. For me what followed was a day of sussing things out, and the fastest growing up I've ever done in a 24 hr period.
To be fair to all of us trainees, a simple brief on 'Pitch Attitude flying' would have avoided the whole debacle and waste of the first days aircraft training (no 'luxury' of a simulator)
From the question asked, it's clear that the issue has not died away, for pilots who are essentially transitioning from mostly VFR to IFR style flights.
For pilot's of larger airplanes knowing the Pitch + thrust/torque/power for different phases of flight and especially for straight and level, is probably the most basic, useful and unfailing tool given to them. It is the mainstay in tackling "flight with unreliable airspeed". It is second nature for a heavy jet pilot to aim for somewhere around 7 deg pitch for level flight the moment the first stage of flaps/slats are extended.
From the discussion and answers given so far, the record is far from clear and the following concepts need clarity:
PITCH ATTITUDE: There should be no ambiguity in the understanding of pitch attitude - it is the angle made between the Longitudinal Axis and the local horizon of the Earth, the longitudinal axis being a straight line that runs in a fore-aft direction and is the axis around which the airplane ROLLS.
LEVEL FLIGHT: refers to flight with no change in altitude, i.e. Vertical Speed (VS) = zero. Level flight can be performed at different speeds and during turns.
Attitude and Heading Reference Units (AHRU) boxes are installed to provide inputs for the PFD. Level attitude i.e. Pitch = 0 and Bank = 0 for the PA 28 is defined in the diagram below:

Once the AHRU is installed and connected and feeding the PFD, then pitch and roll calibration offsets are set as required so as to display Pitch = 0deg and roll = 0deg with the airplane level. These software controlled offsets are available via menu on the GI-125 interface.
Given the above description and 'definitions', an important property of such systems is that they naturally align themselves to the Earth's local horizon, or put another way, they exhibit the behavior of a 'bob' that hangs vertically along the line of gravitational force and the local horizon is at 90deg to this, and this is what the PFD displays. This holds true whether the system contains mechanical gyros mounted in a gimbal, or the ring laser type and is basically governed by thee properties of the inertial gyro and the rotation of then Earth around it's geographical, or True axis.
The upshot of all this is that the pitch attitude and AoA are governed by the laws of Physics and cannot be simply set to match what is convenient to us as doing so would render them erroneous under different circumstances.
As for whether 5 deg is correct - you could check about the calibration offsets as described above - this should not be difficult to ascertain from the shop that did the installation.


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Why do aerobatic planes have symmetrical wings?
Besides the fact that symmetrical wings fly the same inverted as upright are there any other reasons why aerobatic planes prefer symmetrical wings?  Can symmetrical wings achieve a higher critical angle of attack?  Does the large ailerons on aerobatic aircraft have anything to do with it?

Related

BTW, not all aerobatic airplanes have symmetrical wings. Two that I've flown definitely do not, the Cessna Aerobat and the Citabria do not have symmetrical wings. You have to work hard to stay inverted. :)

One goal for most aerobatic planes is neutral pitch stability, which eliminates any pitch response related to air speed, which allows for clean straight lines during dives or climbs without requiring elevator adjustment for speed.
Cambered airfoils produce a pitch down torque which increases with speed, and this would interfere with the goal of neutral pitch stability. This would be another reason for using symmetrical airfoils on aerobatic aircraft.


text:
What is the proper technique for using rudder pedals with toe brakes?
I just had my first flight lesson the other day and I had some issues with using the rudder pedals and toe brakes for taxiing.  For example, how do you steer and brake at the same time when making turns?  I also sometimes inadvertently press the toes brakes when trying to steer the plane. Is there any advice that you can give me to help me coordinate steering with toe brakes? I find that steering the plane on the ground with the rudder pedals is quite foreign to me, I have never had to use this level of foot coordination before.
I am flying a Piper Cherokee with steerable nose wheel and toe brakes.  Also does anyone else have this problem or is it just me?

You will get used to it. If you aren't planning on using the brakes, move your feet down so your toes are near the bottom of the pedals. Make sure you don't have excessive speed (brake before turning, make sure you don't get any faster than a quick-walk speed).

Since you're on day 1 of your training, here's a tip: the answer to the question "does anyone else have this problem?" is always "yes, lots of people" :-)

Unless you have extra long feet, keeping your heels on the floor of the plane is usually sufficient to keep them off the toe brakes.  Or pull your legs back a little and press with the balls of your feet near the middle of the pedal and not the top.  You'll get the hang of it pretty quick.
Learning to relax helps also, otherwise you'll fly with your legs all tensed up and just have the rudder pedals all mashed down all the time.  Very tiring.

You really don't want to have your toes on the brakes as you land!

Heels to the floor all the time, relaxed.  Tips of the rudder pedals used only when needed.  Do NOT ride the  rudder pedals with your feet.  Had a student who put his whole feet on the rudder pedals and nearly landed with the brakes engaged.  Not pretty.  I've head many a new student say the hardest part of flying was taxiing the "damn thing".  Like any control, practice will answer your question.  The best advice I can give is contained in the first two sentences above.  Good luck with your training.


text:
How pitch is changed in harrier jet(vertical landing and take off aircraft)
How pitch is changed in harrier jet and lift is achieved?Is it same principle like conventional fighter jets like f16 etc? What about drones quadcopter etc do they also follow same principle?

F-16 cannot land or takeoff vertically. And what do you mean with "etc"? There are drones with and without wing, they work differently and also here not all drones can land/takeoff vertically

Pitch and roll is achieved by generating forces far away from the Center of Gravity (CoG), causing a moment which in turn pitches or rolls the aircraft. Imagine pushing or pulling on one side of the aircraft in flight: you will accordingly pitch or roll the aircraft depending on where you pushed or pulled.
The question is therefore: How does the harrier (or drones, quadcopters etc.) generate a force far away from the CoG?
1. The Harrier achieves that over ejecting air out of nozzles as far away from the CoG as possible. For this it uses relatively small reaction control nozzles at its wingtips, and at the far front and back. These are pressurized using bleed air from the jet engine. The pilot can individually activate each nozzle up or down in order to generate forces which then will result in a pitching or rolling moment such that the aircraft follows the pilots command. You can see the arrangement in the picture below. Note that this method of generating control forces is only done in hover or near-hover flight. During conventional horizontal flight, the harrier achieves control over its control surfaces, the same way as any other fighter jet.
Also note the big Swiveling nozzles near the fuselage. These generate pure Lift: They generate a lot of thrust upwards to keep the Harrier in the air as the reaction control nozzles are not powerful enough to lift the entire aircraft.  But because these swiveling nozzles are mounted close to the CoG, they cannot be used for roll or pitch control. Thus, the Swiveling nozzles generate the lift during hover-flight, while the reaction control nozzles generate control moments to enable the pilot to control the aircraft. This system is only active during Hover flight (therefore at zero or close to zero forward airspeed). When the pilot wants to fly horizontally, the swiveling nozzles are swiveled backwards, and the reaction control nozzles are deactivated. The Harrier will then fly forwards just as a normal jet would do. In normal horizontal flight, lift is generated with the wings, and control is achieved via the control surfaces, just as a normal jet would do.

Picture taken from Canada aviation museum
2. Quadcopters in principle do the same thing: They generate thrust far away from their CoG by speeding up or down the rotors. Increasing the speed means more thrust, therefore generating a higher force which just as in the case of the harrier generates a moment which pitches or rolls the quadcopter. However they do not have swiveling nozzles, because they do not need to: The rotors of are drone are powerful enough to lift the entire vehicle. Therefore the generation of lift and the generation of control moments of drones are both combined in the rotors. Note the difference to the Harrier: The Harrier needs Lift nozzles, and control nozzles. The Quadcopter can combined both of these in the form of propellers.

It diverts bleed air to valves to control attitude in hover:

Welcome to Aviation.SE! Can you please link to the source of the image?


text:
Minimum distance required to turn at maximum speed of an F-16
What would be the minimum distance required for an F-16 to turn either sideways or upwards in order to avoid a collision (assume an infinitely long wall both length and breadth wise).
Also would it be better for such planes to turn sideways or upwards? Which is faster and requires less distance.

Someone please help me with the tags, I don’t think that they are sufficient.

To clarify, are you asking about the diameter of a 180 degree course reversal?  (Because you only need to turn a few degrees to avoid a collision...)

@MichaelHall : I am assuming an infinitely long wall so turning a few degrees won’t help. Also, I want to know about the radius of a 90 degree course reversal, a 180 diameter would help too.

Ok, I read the wall part, but didn't really get it.  I can't calculate the answer, but rolling inverted and pulling will give the best radius because you aren't fighting gravity.  You get an extra one G from mother earth...

@MichaelHall : So, a downward turn around would be faster and shorter?

Subtracting the time it takes to snaproll 180, yes.  But only for the first 90 degrees of turn.  After that you are working against gravity and your turn radius will increase.  But by then you are parallel to the wall.

@MichaelHall : I didn’t think of the extra G that we would get, so I have half of the answer, the only thing that remains is the distance. Thank You.

@MichaelHall : Being parallel won’t be an issue as I only want to avoid the collision, and after that taking another small turn won’t matter, because maneuvering is the most important part as it takes a lot of time and distance which is difficult at high speeds. Also, with regards to the plane that bombed H & N, it would save most of it’s time by making the fastest maneuver possible.

A level turn will give a constant radius, and may be the best option for 180 deg.

@MichaelHall : Yeah, even that would do but now that I think of it, the downward turn seems more practical.

On the other hand, an upward turn (half-loop) will have gravity helping you slow down, which will decrease the turn radius assuming you're limited throughout by max permissible structural G load. You'd want to pull the power to idle too.

@pericynthion : Even that’s true but since I want to have maximum speed, a downward turn would help.

It'd probably be a good idea to clarify in the question that your scenario has the aircraft not only starting at maximum speed but maintaining maximum speed throughout the maneuver.

@pericynthion : Yup I will do it right away.

Is there any particular reason the aircraft needs to maintain top speed throughout the maneuver, or is that an arbitrary requirement? If it is an arbitrary requirement, that's totally fine, but it would be good to know whether it's arbitrary or there's a reason behind it.

@TerranSwett : As I mentioned in the question, I thought of this when I read about the planes that bombed H & N and I am trying to co-relate things, in order for those pilots in their planes(not F-16s) to take the fastest turn possible to come back alive. So we can say that it is arbitrary requirement as the most important thing is less amount of time and more distance to be covered which can be achieved either by maximum speed or by least possible distance to cover.

According to this F-16 turn performance chart, at the rated maximum airspeed of 800 knots, an F-16 can turn at about 10.5 degrees per second, so a 90° turn would take about 8.5 seconds. The turn radius would be 9,000 feet. Since you specified a 90° turn to avoid an infinite wall, the pilot would have to start their turn at or before 9,000 feet from the wall in order to avoid a collision.
However, this doesn't tell the whole story. The F-16 can't maintain speed in such a turn, and the reduced speed would in turn reduce the turning radius. If the plane, for whatever reason, absolutely had to maintain its maximum speed, then it would be limited to a turn rate of 3.5 degrees per second and a turning radius of 25,000 feet.

If the point of the exercise is to avoid the infinite wall, then bleeding airspeed would be immensely helpful since it reduces your turn radius... go idle, 90 degrees bank, and pull 9 G's; the speed will bleed off rapidly and the turn will be complete much sooner than 9,000'. Or idle & pull 9 G's straight up, bleeding speed in the vertical, adding power as necessary to complete the Immelman.

@RalphJ True, but since the OP was very specific about the "flying as fast as possible" part, I assumed they wanted top speed maintained throughout the turn. Unfortunately, I don't know of any published performance information for any plane that includes variable-speed turns, so you'd either have to simulate the turn mathematically (something that's beyond me), or else get a real F-16 and test it (also beyond me).

@HiddenWindshield : Your assumption was right(should have mentioned it, my fault sorry). Also, could you include the turning downward part so that that I can mark it as the answer.

@RalphJ : Would the pilot experience 9 G’s!! of force ?!?!

@valay_17 Well, it's an F-16... you want max performance, you should expect 9 G's.

@RalphJ : Yeah , hehe silly me.

@HiddenWindshield  If the scenario is to avoid crashing into an obstacle, the idea of maneuvering but only in such a way that the speed can't decay (even if that requirement impedes the ability to avoid death by crashing), has left the realm of reality & entered into an academic, and not particularly interesting, exercise. If you're not allowed to pull max G because doing so would bleed airspeed & reduce the turn radius, then "maintain parameters" has become more important than survival, and it's hard to keep caring about such a hypothetical at that point.

@Valay_17 Unfortunately, no, I can't add the turning radius for a vertical turn. Such information isn't usually published, simply because publishing performance numbers for every single possible maneuver would be impossible. So figuring that out would involve some kind of simulation, as I said.

I'm with @Ralph J on this.  I enjoy entertaining hypothetical scenarios, but this question is a confusing mish-mash of WWII bombers, infinite walls, F-16 max speed, and F-16 best turn rate.  Most tactical aircraft have a best performance "bug out" defensive maneuver that the pilots are familiar with if the stuff hits the fan.  I imagine this would be vastly different for a fighter vs bomber, and I am only qualified to say what an EA-6B Prowler might do.  All else is speculation for what is becoming an increasingly "not particularly interesting exercise".

@RalphJ : I see your point and it is true, I removed the requirement to make the question a less of hypothetical one and more of a factual one.

@MichaelHall : It was quite confusing but I got the necessary information and I totally agree with Ralph J.


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Engine options for the 777-300ER: GE90-110B1 or -115B?
The Wikipedia page on the Boeing 777 says that the 777-300ER can have either the GE90-110B1 or the GE90-115B, however it was my understanding that the 777-300ER does not have engine options and is only available with the GE90-115B.
Furthermore, this unofficial production list confirms that there are no 777-300ER with the -110B1.
With that said, here's my question: has the 777-300ER ever been offered with the -110B1, whether as a factory option or as a retrofit/modification?

I updated the Wikipedia page to show the correct engines and thrust ratings.

According to the EASA Type Certificate Data Sheet (TCDS) of the Boeing 777, only the GE90-115B engines are approved for the 777-300ER:

5. Engines:
Two (2) General Electrical GE90 Turbofan Engines
Models installed: GE90-115B,
EASA Type-Certificate No.: EASA.IM.E.002
Limitations: See Engine Data Sheet No. EASA.IM.E.002

The GE90-110B1 model is listed for the Boeing 777-200LR and 777-200F models. In the Wikipedia table, the engine entry is for all of these models together.

@ymb1 Yes, it's pretty much the same engine with a higher thrust rating.


text:
Where can I find an aircraft's year of certification (airworthiness certificate)?
Is there a way to pull a list of all certified aircraft (of course only valid certifications) including the year of certification please?
For example I am actually trying to identify when CRJ200 PF was certified ?
thx

You may transform the title in a question as this is a Q&A website

The FAA has a listing of all of the Type Certificate Data Sheets for certified aircraft.
So the first thing you need to do is determine the manufacturer. According to Wikipedia, “The Bombardier CRJ100 and CRJ200 are a family of jet-propelled regional airliners, based upon the design of the Challenger CL-600 business jet.” So look up Bombardier on the FAA site, and then open up the models made by Bombardier.
There are lots of CL-600 variants that all use the TYPE CERTIFICATE DATA SHEET NO. A21EA. The TCDS lists the years for each variant. The CRJ200 PF is a marketing variant of one of these, so you’ll have to do some research to find out which marketing variants match the TCDS but this should get you started.

thank you for the advice


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What is the difference between staged and unstaged fuel manifolds?
Also, I would like to know the difference between pilot, primary and secondary fuel flow.

Staged means that fuel is delivered "after launch" instead of immediately.  This terminology is more familiar from staged rockets:

At engine idle conditions, the electronic engine control (EEC) unit sends a signal to the BSV which then shuts off fuel flow to the ten staged fuel nozzles. As a result, the ten unstaged nozzles receive a higher fuel volume resulting in a stronger flame. [More fuel for those ten and none for the others, encouraging combustion: fewer flames, but bigger ones.]  As the engine accelerates above idle, the EEC signal commands the BSV open, allowing fuel to flow to all nozzles [more than the first ten] so the engine can operate at higher power settings.

This is quite like a campfire started with tinder (unstaged, ignites instantly) and then sustained with thicker wood (staged).
"Pilot fuel flow" is hard to google in an aeronautics context for obvious reasons, but it means the same as "pilot flame" for a household furnace or water heater.  It acts like a continuous low fuel consumption spark,
at start-up and low part load, to encourage more vigorous combustion shortly before that is commanded.


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Why is there an altitude limitation on operating the slats/flaps on the A320?
As per the FCOM limitations chapter there is an altitude limitation of 20000 feet for operating the flaps/slats on the A320?
Why this specific altitude?

Without any deeper knowledge I would guess it has something to do with compressibility of air at speeds in higher altitudes

Why would you want to deploy high lift devices at any juncture except for departure and arrival?
Holding is the predominant scenario.
Above 20,000ft ICAO holding speeds are higher thus allowing clean configuration.
Above 20,000ft, at slower speeds, the likelihood of encountering icing on the wings when moisture exists is also a very real consideration (upto about 28,000ft) and ice accretion is not what you want with high lift devices hanging out.
Extending slats/flaps in typical cruise or when we are flying in the Mach regime of flight, say about 29,000ft and above, is something that would cause much grief to the average Airliner, a possible jet upset scenario.
If other reasons already cited such as aircraft certification/cost of certification are a factor - most operators would not need a change from the 20,000ft figure.

any offical reference for your answer ?

Are you looking for official references for a specific part of the answer?  You want ICAO holding tables and Official definitions of icing conditions? I can try editing and adding text to make the underlying logic more obvious. I cannot provide an official source saying "the slats and flaps are not to be or cannot be extended above 20,000ft because . . . "

okay I was mainly trying to get information regarding as to why the manufacturer has kept this altitude limit. Or any other official reference which states why not to take flaps above 20,000.

I’ve been in a situation where ATC tried to slow us down below feasible clean speed above 20000’

I'm sure, but you can always say, "unable due aircraft performance". ATC shouldn't 'penalize' you for this but there can be situations where it is unavoidable, most commonly resulting in pulling you out of the traffic sequence (= possible delay). Most airliner type transports would have the same issue as already discussed. Also, on Boeings of current vintage it is not prohibited to fly below The maneuvering (UP) speed down till minimum maneuver speed (top of yellow bar) tho probably Co. SOP may not allow.  BTW @busriver - what was the circumstance, and was the same asked of other airplanes?


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What are the advantages of using DC electric power over AC, as e.g. done in the EMB 135/145?
In this question I can see the advantages of using AC electric power over DC in large aircraft. However, Embraer decided to produce a "DC aircraft": the ERJ 135/145.
What are the advantages of such a DC power system over the more commonly used AC one?

Note that the ERJ has an AC bus for some avionics systems, which is powered by a static inverter via DC Bus 1. The main power distribution in the aircraft is however 28V DC.

@ymb1 Electrical system description from SmartCockpit: "The DC power system supplies 28 V DC for all aircraft electrical loads
and recharges the batteries. It is the primary electrical power supply
system."

Related: Yan Moir: "DC systems are limited to around 400 amps or 12 kW [...] for two reasons: • The size of conductors and switchgear to carry the necessary current [...] • The brush wear on brushed DC generators becomes excessive" The EMB 145 (400 A) is at the limit. Larger aircraft must use AC or higher voltages (270 VDC). 28 VDC has been used in the 50s. In AC current is null 800 times/second, fully loaded circuits can be switched off more easily.

Now, DC is easier to produce than AC and easily to inverted to AC
To produce AC of a specific frequency, you will need one of below

An engine that rotates at a fixed rate.
A variable transmission box that normalizes the rotation rate.
Produce DC somehow then invert it to AC.

Method #1 is used by most American GE diesel locomotives. As a result, when the locomotive is providing AC power to the train cars, the engine needs to run at a fixed rpm, hence can not run at full rpm and full output. For this reason, a lot of other countries have switched to DC bus for train cars, essentially switched to method #3 (e.g. China uses DC600V for the train bus and it is inverted to 220V/380V 3-phase within each car).
Method #2 I believe is used by most airplanes, because fixing the engine at a certain RPM is simply not possible. The variable transmission is certainly not zero weight and is pretty complex and is certainly a point of failure. It seems like some airplane designs are switching to method #3 as well. They didn't switch to #3 earlier simply because aviation industry relatively is slow on new technology (so is the space industry).
Method #3 is basically what everyone else chooses since the beginning of this century, when semiconductor finally makes it cheap and simple and efficient to invert DC to AC. From small gasoline generators and home air conditioning, to electric cars and trains and ships, whenever the frequency of the power generator doesn't match the consumer, using DC and semiconductor power electronics to bridge the gap is the simple choice.
Most avionics are electronics, and most electronics runs on low voltage DC
Except the gyro, the CRT display, and environment control, everything else runs on DC internally. If you use an AC bus, then every device needs its own converter for it's internal working DC requirement. If you need a converter for each device anyway, then why not a DC-DC one and it's lighter and smaller and possibly cheaper?
Changing voltage used to be easier for AC than DC, now it's sort of the other way.
Before semiconductor, the only efficient way of converting voltage is via a transformer, hence AC. But transformers are heavy, which is why aviation uses 400Hz instead of 50/60Hz: transformers for higher frequencies are lighter and smaller. With modern semiconductor power electronics, you can basically convert DC voltages with near-zero weight, which is certainly desirable for airplanes. Also, semiconductor are made from sand, a lot cheaper than copper that makes a transformer.
DC-DC voltage conversion is more robust than AC-AC
An AC power transformer converts the voltage at a fixed ratio, so when the input side's voltage or frequency fluctuates, it propagates to the output, potentially affecting the downstream devices. DC-DC converters and DC-AC converters outputs at a fixed spec, so the input fluctuations are isolated from the output. This additional protection is certainly desirable for the aviation industry where safety, reliability and fault tolerance are the top of concerns.

While I can believe silicon semiconductor devices are certainly cheaper to manufacture than copper transformers, I don't think it's about the price of the materials. It's rather than semiconductor devices get huge economies of scale. It may sound like "sand" should be cheap, but silicon manufacturers have to use super-ultra-pure silicon dioxide, not just scoop it up from a beach in Atlantic City.

I certainly might be wrong, and I'd love to see a citation.

@RossPresser: Ultra-pure silicon is definitely necessary when you're making CPU's at nanometer scale, but your typical rectifier is a bit less sensitive to small crystal defects. The semiconductor industry has become quite adept at finding a useful second life for many obsolete production lines. As you note, many raw materials are pretty cheap too, so the main cost is just running the old machines (electricity & personnel).

I think your method #2 used by most airplanes is just wrong.  Most airplanes are pure DC, just like automobiles (and often using essentially the same parts).  You might or might not be correct about commercial airliners, but they're only a small fraction of airplanes.  (And I don't see why a competent engineer would use such a system in the first place.)

Vastly easier to synchronize 2+ generators
With DC generators (or AC alternators immediately rectified to DC)... each generator simply has its own voltage regulator set to output the agreed DC voltage.  The regulator, which is simple, well-established tech, simply increases/decreases the generator excitation field to get the correct voltage to come out.  It will do this at any engine or generator speed.  Your car already does this with its alternator.
The only issue is on multi-engine vehicles.  Starting an engine draws a tremendous amount of current.  The generator on the already running engine might overload itself trying to help start the other engine.  However this is easily solved by adding a current-limiting circuit to the regulator, and that can be done entirely with passive components.
Whereas synchronizing AC is super hard
When you have AC distribution, and you want to feed that distribution from 2 generators, it gets byzantine fast.
First, the generators must be synchronized to each other before the second one connects -- both in frequency and phasing.  If not, it's a really bad idea to bring them online.
If the frequency is not matched, extreme current will flow, as each generator tries to "force" the others to run at its own speed. Imagine 2 engines connected with a clutch: they're at different speeds and then you abruptly "pop the clutch".  The engines will be forced into sync, and the forces on the clutch will be tremendous.  Well, the same thing happens, but with electric force which will be tremendous.  Likely, this will simply trip their circuit breakers.
If frequency is matched but phase is not, the generators will still fight each other, as each tries to maul the other into sync.  It's like if the engines were running at the same speed, but the clutch had gears and the teeth weren't aligned.  There will be a big shock, and again that will occur with electric force onto the AC buses.
Synchronizing is straightforward as you saw in the linked video. But since you don't have a flight engineer to watch the 3 lights and turn on the generator at the right instant, this all needs to be automated.  Not so simple - lots of complex things to go wrong.
Once synchronization has been achieved, there is a reactive force flowing between all generators to keep each generator in sync and phase-lock. If a generator starts to overspeed, its share of total load will increase, and this load will make its engine bog down.  If a generator underspeeds, load will come off it entirely and it will speed up.   At least that's how it works with engines *whose primary load is the generator. The tail wags the dog: the grid wags the engine.
... even harder when engines must be free to run at variable speeds
You caught the part above where the 2+ generators will "fight" to force each other into sync.  If the generators are hard-coupled, this means they are trying to force the entire engines into sync also, like an electric version of the cross-shaft on a V-22 Osprey.
That "tail wagging the dog" is fine when the engine's main output is the generator.  But the plan falls apart if the generator is an auxiliary load.
So that means thrust-generating aviation engines can't be hard-coupled to their generators.  There must be a variable-speed mechanical coupling that frees the generator to run at its ideal/target speed.   This is more complexity still, and more stuff to break.
This concept of a 'mechanical coupling' also exists in the DC generator, but this happens electrically -- the voltage regulator adjusts field excitation to suit engine speed and electrical loads. That's what voltage regulators already do.  Easy as pie!


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Should one use mainly the rudder or the ailerons combined with rudder to go back to center line on short short final?
My pattern work is improving but there is one thing I consistently miss: I have a very hard time staying aligned with the runway on short final, say after passing the airport fences. When the nose points left or right, should I correct primarily with rudder or with ailerons using rudder just as usual to stay coordinated?
Cross wind is not a factor at this point because I miss even when wind is calm.

"Stop jerking that yoke and use  your feet" - My instructor, every time we fly together...

Best to be coordinated in the pattern with a proper approach speed above stall.  If the nose goes a little off line (but the plane is on track), use that rudder

Rudder.  It is amazing how much even a tiny puff of wind can move the nose off line.
If you are on "short short", just clearing the fence, your momentum will carry you onto the runway even if you are almost sideways. (But this is not good for the landing gear).
Most important here is to round out correctly at the proper airspeed (the earlier you get your approach speed right the better).
It is not unusual at all for the nose to move offline, keep flying the plane all the way down using rudder corrections to hold the nose to the line.
Only if your plane drifts towards one side or the other do we need ailerons, and this is how we do a crosswind landing:  aileron holds drift, rudder holds line.
A light GA aircraft will usually pivot faster than it will drift.
The physics is that the torque turning it requires less force than to move the whole thing sideways.
But air is rarely completely calm, so be ready to use your rudder and ailerons and continue using them until the wheels stop.

Thanks Robert, Crystal clear. I was hardly using any rudder so no wonder I was all over the place. Correcting only with ailerons (big corrections) makes plane drift even more due to adverse yaw. So as long as I am still tracking centerline, I need primarily only (small) rudder corrections. If track is drifting off centerline then use yoke to bring it back on track. Thanks again for your time and patience it helped me a lot.


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If aircraft specific energy is a combination of kinetic and potential energy, why is altitude not a variable in the energy-maneuverability theory?
The Energy-Manueverability formula is
$$ P_S = V \left( \frac{T - D}{W} \right) $$
with velocity $V$, thrust $T$, drag $D$ and weight $W$.
$P_s$ represents specific energy, which is a combination of potential and kinetic energy. What I want to know is this: if specific energy is a combination of kinetic and potential energy, why is altitude not a part of the formula?

It is. Potential energy is MgH, and the H is altitude (Height). Although Specific Energy is actually specific kinetic energy plus specific potential energy, which is actually energy per unit of mass. That's so we can compare specific energy of aircraft with widely differing masses with one another. The formula in your link is NOT specific Energy, it is Ps, or specific Power, which is different.

I’m voting to close this question because it is based on a fundamental misunderstanding: asking why the equation for specific power doesn't include a term expected to be found in the equation for specific energy.

It is. Potential energy is MgH, and the H is altitude (Height). Although Specific Energy is actually specific kinetic energy plus specific potential energy, which is actually energy per unit of mass. That's so we can compare specific energy of aircraft with widely differing masses with one another. The formula in your link is NOT specific Energy, it is Ps, or specific Power, which is different.


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How to compute the change in static temperature using only altitude?
I'm given an initial altitude of FL290 in ISA conditions, and the aircaft is said to climb to reach FL310. How can I use this to calculate the change in static temperature between the two flight levels?
I know that the formal term is the lapse rate and generally lapse rate decreases around 2 degrees Celsius per 1000 feet of climb.
Would I use a ISA temperature table to figure out the temperature for the initial altitude and then use the lapse rate to calculate the change in temperature when it climbs to reach FL310?

This sounds a lot like a homework question. Did you Google how the temperature depends on altitude in ISA conditions?

Could you include your current state of research? It will help us to know how we must answer

I found the answer, it's literally looking at ISA temperature table of the initial FL. The lapse rate is 2degrees per 1000 feet of climb. You would see what the initial temperature is for your FL and then you minus the lapse rate for the climb that you are given. So in this case, the lapse rate would be 4degrees as it climbs 2000 feet.

Why are you even looking up the initial temperature if you are only interested in the difference? The difference is simply the lapse rate times altitude difference no matter what the absolute values are, isn't it?

Oh yes, you are right. I never thought about that approach. Thank you for sharing.

But careful! The same problem at altitudes above ~FL360 will have a different answer.

Yes, above FL360 the temperature remains constant, so there would be no change if we are comparing two altitudes above FL360 for temperature change.


text:
Is the "wing area" of a biplane the projected area or the total area?
When you specify the wing area of a biplane, do you specify the planform area (the projected area) or do you specify the effective area of both the wings?

I could have sworn we had this exact question, or a very similar one about interference and effective wing area, but I can't find it.

It's a mixture of both: You add the projected area of both wings, measured separately, without overlap.
The effective (wetted) area is used for friction drag calculations only.


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What mode is the Boeing 777's autothrottle in right after touch down?
This question came to my mind when I saw the Emirates B773 (Dubai on Aug 3rd 2016) accident.
I saw a couple of 777 cockpit videos and I saw that autothrottle (A/T) is widely used during landing and they just turning the autothrottle knob left or right to set the speed. Question. Does anyone know what mode is the 777 in right after touch down? Especially the A/T? As far as I know the aircraft goes to roll out mode (whatever that means). Lets assume they initiated a go around right after touch down for whatever reason. The pilot assisting just turned the knob again (as usual) instead of pushing TO/GA but it was ineffective as A/T was disengaged automatically. So yes, it is guessing without any knowledge so lets focus on my question. What mode is the A/T in right after touch down?

During the flare somewhere between 25' and 50', the A/T retards the thrust levers to idle. They remain in idle mode until reverse thrust is selected which automatically disconnects the A/T.
In the case of Emirates 521, eyewitnesses observed the aircraft do a bounced landing and then attempt a go-around reaching a max altitude of about 150'.
Because the aircraft had touched down, it can be assumed the A/T had automatically gone to idle, and it appears the thrust levers were not manually advanced. The aircraft then settled back on the runway as the gear was being retracted.
More speculation here:  Emirates B777 crash was accident waiting to happen

a pilot colleague observed exactly what happened as he was there, waiting in his aircraft to cross runway 12L. The B777 bounced and
  began a go-around. The aircraft reached about 150 feet (45 metres)
  with its landing gear retracting, then began to sink to the runway.
This suggests that the pilots had initiated a go-around as they had
  been trained to do and had practised hundreds of times in simulators,
  but the engines failed to respond in time to the pilot-commanded
  thrust. Why?
Bounces are not uncommon. They happen to all pilots occasionally. What
  was different with the Emirates B777 bounce was that the pilot elected
  to go around. This should not have been a problem as pilots are
  trained to apply power, pitch up (raise the nose) and climb away.
  However pilots are not really trained for go-arounds after a bounce;
  we practise go-arounds from a low approach attitude.
Modern jets have autothrottles as part of the autoflight system. They
  have small TOGA (take off/go-around) switches on the throttle levers
  they click to command autothrottles to control the engines, to deliver
  the required thrust. Pilots do not physically push up the levers by
  themselves but trust the autothrottles to do that, although it is
  common to rest your hand on the top of the levers. So, on a go-around,
  all the pilot does is click the TOGA switches, pull back on the
  control column to raise the nose and — when the other pilot, after
  observing positive climb, announces it — calls “gear up” and away we
  go!
But in the Dubai case, because the wheels had touched the runway, the
  landing gear sensors told the autoflight system computers that the
  aircraft was landed. So when the pilot clicked TOGA, the computers —
  without him initially realising it — inhibited TOGA as part of their
  design protocols and refused to spool up the engines as the pilot
  commanded.

thanks the answer it is really great to talk to a real 777 pilot. I don't have PPL yet so I am not a pilot but from my perspective I would rather like to have a full control during landing, including thrust. How do you feel about having A/T engaged all the time (if it is engaged all the time)? Do you like the idea?

I like having A/T on all the time. It is normal SOP to always have it on but it can be disconnected anytime by a small thumb switch on either Thrust Lever. At my airline we keep one hand on the thrust levers at all times when below 1000' above ground. When I do a go around, I always advance the trust levers manually and say "Go Around, Flaps 20", and then I press the TOGA switch after the Thrust Levers are well forward.

Do you have to hold the levers forward for a certain amount of time? On the Amsterdam 737 crash the plane went into flare mode unexpectedly. They pushed the levers forward but since they didn't hold them there long enough the A/T put them back to idle

Yes, you have to hold them forward manually as they will go back to idle until another mode can be engaged. A bounce and go landing is rather unusual but I belive it would have been possible to engage TOGA mode after a 5 second delay.

It should be mentioned that this describes Boeing logic. Airbus logic is very different (the A/T does not move the levers there, TO/GA does not have a switch, but is selected by moving the levers full forward and the pilots must move the levers to IDLE manually to disengage the A/T, otherwise it remains on even on the ground).

Yeah this has always seemed like a flaw in the Boeing system to me - touching down shouldn't disable the TOGA button, and I can't understand the logic of it. A pilot pressing TOGA expects the engines to spool up, and at an absolute minimum, pushing that button should not quietly do nothing: at least alert the pilot that nothing is going to happen.

@JonStory -- seconded -- if nothing else, it makes the flow for an intentional T&G different from the flow for a missed approach...

That Emirates B777 crash was a classic case of a flight crew losing sight that they were the ones flying the jet; the AFCS and AT should simply do what they tell them to do as opposed to these systems flying the plane.  AFCS and ATs, like a lot of other cockpit automation have the ability to make a good flight crew better and a poor flight crew dangerous.


text:
Is it possible to estimate airspeed on top and bottom sides of a wing at zero angle of attack?
Assuming a flat bottom wing moving through the air at say 50km/h and at zero degree angle of attack, what will be the likely airspeed above and below the wing?
I know this will be affected by camber and maybe wing chord too. But is there like a proportional estimate for specific wing camber?
I haven't got much knowledge about wing maths, but a formula would be appreciated.
Applying Bernoulli's equation requires the relative airflow above and below the wing. The things is, I'm trying to experiment with the fact that given atmospheric pressure, the two different airflows, and the wing area, one can actually determine the pressure difference between the top and bottom surface using Bernoulli's equation and also the total force holding the plane up by getting the product of the pressure difference and the wing area. So what I'm trying to do is estimate the lift force on my theoretical airplane model at a particular wind speed. I want to use this to estimate the minimum airspeed required for normal flight 'without flaps'.

Might be worth also asking this at physics.stackexchange.com to get an in depth answer of fluid dynamics.

We would need more information on what the rest of the wing would look like. Apart form the bottom.

There isn't just a single airspeed on top and another airspeed on bottom. Airspeed varies continuously over the top and bottom surfaces; for example see https://www.mh-aerotools.de/airfoils/velocitydistributions.htm

That page also shows that an airfoil can be giving a lifting force even though speed of air flow over large parts of both the top and bottom is greater than the speed of the undisturbed airflow.

Angle of attack has a large influence on speed of the air flow over the wing.

Okay. I just thought there was a correlation between camber  and the faster flowing air above the wing. Thank y'all.

"So what I'm trying to do is estimate the lift force on my theoretical airplane model at a particular wind speed." I might suggest that you edit the title and first three paragraphs of the question to more accurately reflect what you're asking for. Without knowing more about the model, it's difficult to answer this question comprehensively. Asking about lift on an entire airplane is different than asking about lift on a wing.

OK if it is lift that you would like to compute, this is the way it is commonly done:
$$ L = C_L * \frac {1}{2} \cdot \rho \cdot V^2 \cdot A $$
With

L= lift [N]
$C_L$ a lift coefficient depending on aerofoil shape and angle of attack $\alpha$ [dimensionless]
$\rho$ = air density [kg/$m^3$]
V = airspeed (of the aircraft) [m/s]
A = wing area [$m^2$]

If you would like to use a flat bottomed profile, you could use Clark Y. This image is a bit fuzzy but you could construct a straight line $C_L - \alpha$ from the graph.
Image source
At $\alpha$ = 0 the $C_L$ is about 0.4, so at sea level, with an airspeed of 100 m/s and a wing area of 10 $m^2$ the lift would be:
$$ L = 0.4 \cdot \frac {1}{2} * 1.225 * 100^2 * 10 $$
= 24,500 N. So the pressure differential over the wing area is 2,450 N/m$^2$ If this would be from increased dynamic pressure over the wing only, the air speed on top of the wing would be:
$$ 2,450 = \frac {1}{2} \cdot \rho \cdot (V_{top}^2 - V_{bottom}^2) => V_{top} = \sqrt{\frac{2,450 \cdot 2 }{ 1.225} + 100^2} = 118.3 m/s$$
In that particular case, at angle of attack zero, with no skin friction or boundary layer, static pressure underneath the wing equal to atmospheric pressure etc etc, the speed under the flat wing surface would be the airspeed = 100 m/s and over the wing would be 163.2 m/s. But the creation of aerodynamic lift is way more complicated than only considering the speeds over and under a wing section and assuming that lower surface pressure = atmospheric pressure, that is why it is done with the $C_L - C_D$ graphs.

The short answer is that it is possible, by way of knowing the pressure distribution and applying the Bernoulli equation to relate the pressure and the velocity.
More specifically to your question, I'm not aware of any published correlation between camber and air velocity (nor do I think it'd have much practical application), but you could come up with your own by running a variety of geometries through XFOIL for a given airfoil geometry (maybe a Clark Y of varying camber for a flat-bottomed design) and applying Bernoulli on the calculated pressure distribution for whatever freestream atmospheric conditions and chord length you want.
Another note: You asked specifically about a wing, not an airfoil. A wing will have lots of other effects contributing to variations in velocity over its surface; there is no easy way to account for all of them.

Applying Bernoulli's equation requires the relative airflow above and below the wing. The things is, I'm trying to experiment with the fact that given atmospheric pressure, the two different airflows, and the wing area, one can actually determine the pressure difference between the top and bottom surface using Bernoulli's equation and also the total force holding the plane up by getting the product of the pressure difference and the wing area.
 So what I'm trying to do is estimate the lift force on my theoretical airplane model at a particular wind speed. I want to use this to estimate the minimum airspeed required for normal flight 'without flaps'.

Yes these are usually available in $C_L$ - $C_D$ data. You would look those up for a particular wing cross section, just take an old NACA profile. By the way, it would have been better format had you posted the contents of this answer into your question, by editing it.


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how to simulate the performance parameters wand EGT parameter?where can i get the data?
I went through a lot of research papers and (kind of) understood the parameters needed for Engine Condition Trend Monitoring. From what I've understood, I need N1speed,N2 speed, Pitch, AOA, Exhaust Gas Temperature, Fuel Flow, Low Pressure Fan Speed, High Pressure Rotor Speed, Engine Pressure Ratio and EGT Margin data.
I'm doing this as a part of my Mtech project and I need some sample data to start working. Also, please correct me if I'm wrong because I'm very new to all this.

Pitch and angle of attack are completely unrelated to the engines. The other items on your list do look relevant for jet engines.

Also n1 speed and low pressure fan speed are identical. N2 speed and high pressure rotor speed are identical.


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What effect does the angle of attack have on lift and drag?
In general, what effect does the angle of attack have on lift and drag?
I understand the the B-25 take-off run was normally in excess of 1500 ft, the exact value dependent upon load, density altitude, pilot skill, etc. The B25s used in the 1942 Tokyo Raid had to take off from the Hornet deck in about 500 ft. I've heard that with coaching from a USN pilot, they learned to optimize the AoA so all 16 made it. So I am interested to know more about the trade-off of lift vs. drag.

I understand the the B-25 take-off run was normally in excess of 1500 ft, the exact value dependent upon load, density altitude, pilot skill, etc.  The B25s used in the 1942 Tokyo raid had to take off from the Hornet deck in about 500 ft.  With coaching from a USN pilot, they learned to optimize the AoA so all 16 made it.  So I am interested to know more about the trade-offof lift vs. Drag.

Ymb1 is correct.  I could not find documentation as to how much weight was removed, but according to the books "30 Seconds Over Tokyo" and "I Could Never be so Lucky Again," items removed were radios, tail guns (replaced by painted broom sticks) and the secret Norton Bomb sight. I was looking for general information like that supplied by Michael Hall, below.

As angle of attack increases, both lift and induced drag will increase until sometime after L/D max is achieved.  Beyond that the lift will decrease dramatically.  This fundamental principle is the same for Doolittle's raiders as it is for a Cessna 150.


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What are the take-off parameters for the B-25 Mitchell?
What is the take-off distance and speed in standard atmosphere (59°F, 29.92 inHg, 0% humidity) for the B-25 Mitchell with max, minimum, or average payload?

You can find the full POH here, no wind, standard atmosphere, at gross weight you are looking at 3800 ft. of ground roll and 4700 ft to clear a 50 foot obstacle. Take a look at the charts for the other weights as well as other runway surface types.

(source)